Speed control of stranding equipment



July 23, 1968 w. J. LUYCAS 3,393,503

SPEED CONTROL OF STRANDING EQUIPMENT Filed Dec. 20, 1966 CD/IDAYOFF REEL MAIN DRIVE IN R R 22 0T0 MOTOR F64 TACHOMETER GENERATOR 7o TACHOMETER 92 5 GENERATOR 56 5a INVERSE 72 FUNCTION GENERATOR scR SPEED REGULATOR INTEGRATING CIRCUIT INVENTOR WlLLlAM J. LUCAS 514. 9am, Mud mu.

ATTORNEYS.

United States Patent O ABSTRACT OF THE DISCLOSURE ice Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

Brief description of the drawing In the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the views:

stranding machines used for making cableshave their 3 speed limitedby the centrifugal effect which results from the weight of the bobbins. p i v With lighter bobbins, the machine can be safely run at higher speeds. This invention provides an automatic control for the speed of cable-strandingmachines; and

the control talresadvantage of the fact 'thatthe bobbins become lighter as' the wire on them is used up. The invention increases the speed of a stranding machine progressively and proportionately as the bobbins become lighter. Tachometer generators on the stranding machine motor and on one of the bobbins have their output connected with a speed controller for the motor, andthe speed controller responds to differences between the tachometer generator outputs. j

Brief description of the invention This invention provides an improved speed control for a cable-stranding machine which has-co-ordinated power means for advancing a cable and supplying strands for the cable. In the preferred embodiment, a capstan that advances the cable is driven by the same motor that drives rotors of the strand supply sections through appropriate gearing or other motion-transmitting connections; but it will be understood that separate motors with pro vision for co-ordinating their speeds can be used and come within the expression motor means.

As the wires on bobbins of the strand supply rotors are payed out, the total weight of each bobbin becomes less, and the rotor by which the bobbins are carried can run safely at higher speed. The invention speeds up the strand supply rotors in proportion to the weight reduction of the bobbins, and the weight reduction is preferably determined by the change in diameter of the reel of wire on the bobbin;

It is suificient to rely'upon the wire on any one bobbin of onesection of the-stranding machine because-all of the bobbins are of the same capacity and all of them contain substantially the sameamount of wirewhenthe stranding operation is started. A bobbin rotates progressively faster as the amount of wire decreases, because of the reduced diameter of the reel of wire. This invention takes advantage of this increase in bobbin speed to determine the amount of reduction in weight of the bobbins and to determine the extent to which the rotor that carries the bobbins can be increased in speed with safety.

In order to maintain a constant lay ofthe strands, any increase in-the speed of the rotors that carry the bobbins must be accomplished by a corresponding increase in the speed at which the cable advances axially. An important feature of the invention relates to the apparatus for co-ordinating changes in the orbital speed of the bobbins and the axial speed of the cable.

By increasing the speed of a cable-stranding machine as it becomes safe to do so, the output of the machine is increased with resulting reduction in the cost of cable manufacture.

FIGURE 1 is a diagrammatic view of cable-stranding equipment having the automatic speed control meansof this invention; and p FIGURE 2 is a wiring diagram for the speed control means of the apparatus shown in FIGURE 1 Detailed description of the invention The stranding equipment includes a capstan 10 which includes-two drums. 12 and 14 thatrotate on parallel axles and-that are driven through a gear box 16 and gearing 18 for transmitting motion from they gear box to both of the drums 12 and 14. Power is supplied to the gear box 16 from a variable speed transmission 20 which is driven by a motor 22 through a jack shaft 24.

The motor 22 is connected with the jack shaft 24 through belt-and-pulley connections 26; and the jack shaft 24 is connected with the input end of the transmission 20 by other belt-and-pulley connections 28. It will be understood that the expression belt-and-pulley connections is used in a broad sense to describe fiat and V-belt drives, either single or multiple, and also chain-andsprocket connections.

A cable 30 passes around the capstan drums 12 and 14; and the rotation of these drums advances the cable 30 axially at a controlled speed which depends upon the speed of the motor 22 and the adjustment of the variable speed transmission 20. Wire strands for the cable 30 are supplied from stranders 32, 34 and 3-6. The strander 32, for example, may supply 12 wires to the cable. The strander 34 may supply 18 wires; and the strander 36 may supply 24 wires. It will be understood that there may be other sections of the stranding equipment, for example stranders for supplying 30 wires beyond the strander 36, and other layers of wire depending upon the desired size of the cable. Also there may be another section ahead of the strander 32 for supplying, for example, 6 wires. Thus the stranders 32, 34 and 36 are merely representative of successive sections of wire stranding equipment for applying layers of wire to a cable.

Each of the stranders 32, 34 and 36 includes a frame 40 which supports a plurality of bobbin holders 42 at angularly spaced locations around the cable 30. Only one bobbin holder 42 is shown in the drawing for each frame 40 in order to simplify the drawing. These stranders are of well-known construction in cable-stranding equipment and the details of their construction form no part of the present invention. It is sufiicient to understand that the frame 40 rotates about an axis substantially coincident with the axis of the cable 30 and that the bobbin holders 42 have orbital movement around the cable 30. A bobbin 44 on the bobbin holder 42 supplies wire to the cable as the cable is advanced through the frame 40, and the lay of the wire depends upon the axial speed of the cable 30 with respect to the orbital speed of the bobbin 44. The same lay can be obtained with faster cable movement provided the orbital movement of the bobbin 44 is increased proportionately.

The frame 40 is rotated by power supplied from the jack shaft 24 through motion-transmitting connections 48 which may consist of gearing or belts or any other conventional means for transmitting rotary motion from one element to another. Such drives of successive stranders from a common power source are also well known and Patented July 23, 1968 their particular construction forms no part of the present invention.

Since the bobbin-carrying frame 40 of each of the stranders 32, 34 and 36 is driven from the same jack shaft 24 through similar motion-transmitting connections 43, all of the frames 40 rotate at speeds depending on the lay of the wires for each layer in the cable. Since the stranders 32, 34 and 36 are driven from the same motor 22 as drives the capstan 10, the axial speed of the cable 30 and the orbital speed of the bobbins 44 remain in constant coordinated relation with one another.

There is a tachometer generator 50 operatively connected with at least one of the bobbins 44 in at least one of the stranders 32, 34 and 36. In FIGURE 1 there is a tachometer generator 50 connected with a bobbin 44 of each of the stranders 32, 34 and 36. In the operation of this invention, only one of the tachometers 50 is used at any particular time. The reason for having a tachometer 50 on each strander is that the operation of the stranding equipment for making different kinds of cable may use different ones of the stranders on different occasions and the provision of a tachometer generator 50 on each strander insures that there will alway be a tachometer generator which can be used for the purposes of this invention regardless of which strander or group of stranders is used for a particular cable.

In describing the tachometer generator 50 a operatively connected with the bobbin 44, it will be understood that the type of connection is unimportant. It is sufficient that the output of the tachometer generator 50 corresponds to the speed of rotation of the bobbin 44. The connection may be a mechanical one, as by a jaw clutch, or it may be a magnetic clutch, or the generator output may be produced by rotation of the bobbin 44 through a magnetic field.

The rotating frame 40 has slip rings 54 connected to the tachometer generator to provide conductors for brushes 56 which carry the generator output to a conductor circiut 58 of a speed controller, which will be described in connection with FIGURE 2.

With the stranding equipment of FIGURE 1 operating at a constant axial speed for the cable 30, the lineal speed of the wire passing from each bobbin 44 is constant; but as the diameter of the reel of wire remaining on a bobbin 44 decreases, this same lineal speed causes a faster rotation of the bobbin 44. This increases the output voltage of the tachometer generator 50.

The reduction in diameter of the reel of Wire on each bobbin 44 represents a decrease in weight of wire carried by the rotating frames 40 and a reduction in the centrifugal effect on the rotating frames. The reduced centrifugal effect makes it safe and practical to rotate the frames 40 at higher speed.

By increasing the speed of the motor 22, the axial speed of the cable 30 and the rotary speed of the frames 40, both increase without changing the lay of the wires. Thus the output of the stranding equipment can be increased; and with properly designed speed controllers, the stranding equipment can increase in speed automatically so as always to run at a maximum, optimum speed which depends upon the Weight of wire carried on the bobbins of the rotary frames 40.

FIGURE 2 shows a wiring diagram for the stranding equipment illustrated in FIGURE 1. To simplify the drawing, the wiring diagram is a single-wire diagram. The operative connection between the bobbin 44 and the tachometer generator 51) is indicated by the reference character 64. The slip rings 54 connect with the conductor circuit 58. This circuit supplies the voltage output of the tachometer generator to a voltage divider or inverse function generator 66. Another tachometer generator 70, driven by the motor 22, has its output voltage supplied to the inverse function generator 66 by a conductor circuit 72. The construction of the tachometer generator 70 may be the same as that of the tachometer generator 50. It may be operatively connected with the motor 22 in the same Way, and it may, if desired, be built into the motor 22, that is, it may be a coil of the motor 22.

The inverse function generator 66 supplies a control signal, through a conductor circuit 74, to an integrating circuit 76 which controls a silicon-controlled rectifier 78, connected with the field of the main drive motor by a conductor circuit 82. Thus the speed of the motor 22 can be regulated by the relative outputs of the tachometer generators 50 and 70 so as to change the motor speed 22 to compensate any imbalance of the output of these tachometer generators 50 and 70.

The preferred embodiment of the invention has been illustrated and described, but changes and modifications can be made and some features can be used in different combinations without departing from the invention as defined in the claims.

What is claimed is:

1. Cable stranding equipment including in combination a strander comprising a rotatable frame, a bobbin holder on the frame, feed means for advancing the cable, motor means driving the bobbin holder frame and the feed means at coordinated speed dependent upon the desired lay of the strands, and control means responsive to reduction in the amount of wire on a bobbin holder for increasing the speed of the motor means to drive the bobbin holder frame and the feed means at progressively higher speed and in substantially constant speed coordination with one another.

2. The cable stranding equipment described in claim 1 characterized by a plurality of bobbin holder frames at successive locations along the path of the cable for applying successive layers of strands to the cable, the control means being operatively connected with only one bobbin on only one of the bobbin holder frames.

3. The cable stranding equipment described in claim 1 characterized by the rotatable frame and the feed means being driven by a common motor, and at least one of them being connected with the motor through a variable speed transmission that is adjustable to change the relative speed of the rotatable frame and the motor with respect to one another to change the lay of the strands on the cable.

4. The cable stranding equipment described in claim 1 characterized by the control means including a generator responsive to the speed of rotation of a bobbin on one of the bobbin holders, another generator responsive to the speed of the motor means, and an inverse function generator to which the outputs of the other generators are supplied.

5. The cable stranding equipment described in claim 1 characterized by the control means including a generator, an electric circuit having an output responsive to the speed of the motor means, and an output comparator connected with said electric circuit and connected also with the output of said generator for comparing motor and bobbin speeds.

6. The cable stranding equipment described in claim 1 characterized by the control mechanism including a comparator, a first generator responsive to the speed of rotation of a bobbin on one of the bobbin holders, a second generator that supplies a reference output, means for integrating the outputs of the generators, and a speed regulator for the motor means responsive to the means for integrating the outputs of the generators.

7. The cable stranding equipment described in claim 1 characterized by the control means including a tachometer generator rotated by a bobbin as the bobbin is rotated by the paying out of wire therefrom, another tachometer generator rotated by the motor means, a voltage divider to which the output of both generators is supplied for comparison, and means responsive to voltage differences at the voltage divider for changing the speed in a motor means in a direction to compensate for the voltage ditference.

8. The cable stranding equipment described in claim 7 I characterized by the control means also including a silicon controlled rectifier in the field circuit of the motor means and responsive to voltage from the voltage divider, the silicon controlled rectifier being correlated with the field of the motor means and with the voltage divider to increase the speed of the motor means in response to output from the bob-bin tachometer generator in excess of the output of the tachometer generator of the motor means.

9. The cable stranding equipment described in claim 8 characterized by the control means also including an integrating circuit to which voltage from the voltage divider is supplied, the silicon controlled rectifier being connected with and responsive to the output of said integrating circuit.

References Cited UNITED STATES PATENTS Finkelstein 5758.36 XR Somerville 57-5 8.34 Reichelt 57-93 XR Nelson et al. 5792 XR MacCreadie 57-94 XR Delp 5766.5 Kerr 576 Ash 5793 XR FRANK J. COHEN, Primary Examiner.

DONALD E. WATKINS, Assistant Examiner. 

